1. Field of the Disclosure
The technology of the disclosure relates to distributing power to remote units in a distributed antenna system.
2. Technical Background
Wireless communication is rapidly growing, with ever-increasing demands for high-speed mobile data communication. As an example, so-called “wireless fidelity” or “WiFi” systems and wireless local area networks (WLANs) are being deployed in many different types of areas (e.g., coffee shops, airports, libraries, etc.). Distributed communications or antenna systems communicate with wireless devices called “clients,” which must reside within the wireless range or “cell coverage area” in order to communicate with an access point device.
One approach to deploying a distributed antenna system involves the use of radio frequency (RF) antenna coverage areas, also referred to as “antenna coverage areas.” Antenna coverage areas can have a radius in the range from a few meters up to twenty meters as an example. Combining a number of access point devices creates an array of antenna coverage areas. Because the antenna coverage areas each cover small areas, there are typically only a few users (clients) per antenna coverage area. This allows for minimizing the amount of RF bandwidth shared among the wireless system users. It may be desirable to provide antenna coverage areas in a building or other facility to provide distributed antenna system access to clients within the building or facility. However, it may be desirable to employ optical fiber to distribute communication signals. Benefits of optical fiber include increased bandwidth.
One type of distributed antenna system for creating antenna coverage areas includes distribution of RF communications signals over an electrical conductor medium, such as coaxial cable or twisted pair wiring. Another type of distributed antenna system for creating antenna coverage areas, called “Radio-over-Fiber” or “RoF,” utilizes RF communications signals sent over optical fibers. Both types of systems can include head-end equipment coupled to a plurality of remote units (RUs), which may include an antenna and may be referred to as an RU. The RUs each provides antenna coverage areas. The RUs can each include RF transceivers coupled to an antenna to transmit RF communications signals wirelessly, wherein the RUs are coupled to the head-end equipment via the communication medium. The RF transceivers in the remote units are transparent to the RF communications signals. The antennas in the RUs also receive RF signals (i.e., electromagnetic radiation) from clients in the antenna coverage area. The RF signals are then sent over the communication medium to the head-end equipment. In optical fiber or RoF distributed antenna systems, the RUs convert incoming optical RF signals from an optical fiber downlink to electrical RF signals via optical-to-electrical (O/E) converters, which are then passed to the RF transceiver. The RUs also convert received electrical RF communications signals from clients via the antennas to optical RF communications signals via electrical-to-optical (E/O) converters. The optical RF signals are then sent over an optical fiber uplink to the head-end equipment.
The RUs contain power-consuming components, such as the RF transceiver, to transmit and receive RF communications signals and thus require power to operate. In the situation of an optical fiber-based distributed antenna system, the RUs may contain O/E and E/O converters that also require power to operate. As an example, the RU may contain a housing that includes a power supply to provide power to the RUs locally at the RU. The power supply may be configured to be connected to a power source, such as an alternating current (AC) power source, and convert AC power into a direct current (DC) power signal. Alternatively, power may be provided to the RUs from remote power supplies. The remote power supplies may be configured to provide power to multiple RUs. It may be desirable to provide these power supplies in modular units or devices that may be easily inserted or removed from a housing to provide power. Providing modular power distribution modules allows power to more easily be configured as needed for the distributed antenna system. For example, a remotely located power unit may be provided that contains a plurality of ports or slots to allow a plurality of power distribution modules to be inserted therein. The power unit may have ports that allow the power to be provided over an electrical conductor medium to the RUs. Thus, when a power distribution module is inserted in the power unit in a port or slot that corresponds to a given RU, power from the power distribution module is supplied to the RU.
RUs may also provide wired communication ports or provide other services, each of which may require power consumption at the RU. Regulations in the United States require that no more than one hundred watts of power be provided over the electrical conductor medium. However, certain RUs may require more than one hundred watts to support all the services within the RU.